郑州市2001~2007年城市扩张过程中城市用地景观特征分析

城市用地景观对理解城市扩张过程中土地利用的内部特征及其动态变化具有重要意义。利用2001年Landsat7和2007年Spot4影像,采用人工神经网络方法,提取郑州市土地覆被变化信息;并利用景观指数中的平均斑块面积指数、景观形状指数、平均分维指数和平均连接度指数对土地利用景观沿主要方向进行梯度分析。揭示了城市扩张与土地利用的景观变化是一个过程的两个方面;主要经济发展区已成为城市空间扩张的推动力,在提高平均地块面积和地块连通性方面起到一定积极作用,在距市中心10 km范围内紧凑度提高,整体上松散式和紧凑式扩张并存。

Urban Expansion and Landscape Characteristics of Land Use in Zhengzhou City Dring 2001-2007

Rapid urbanization, especially the speed and scale of the current Chinese urbanization, requires detailed understanding of spatial characteristics of the changing of urban landscape. This has a significant implication for rational and effective urban land use. The purpose of this paper is to derive the information of the landscape change during the spatial expansion of Zhengzhou City during 2001-2007. We detected the change of land cover avail of the remote sensed imageries of Landsat7 ETM and Spot 4. Further, we calculated the landscape matrices of mean patch size, landscape shape index, landscape fragment index, and contiguity index to measure the size of land plots, compactness of the developing, shape and connectivity respectively. In order to show the heterogeneous character of the spatial expansion, the gradient analysis was conducted in the range of 20 km radius centered the place nearby the city center, Erqi Square. The change of detection of land cover illustrated that, during that period, urban land use increased 70.6 km² at the average annual rate of 4%, and the east, northeast and southeast were the main urban land use directions of urban expansion. The speed of expanding of the east part was nearly as two times as that of west part. The landscape matrix analysis showed that the size of land parcels increased in general, yet with a great variation. Generally, the change of landscape and urban expansion are correlated. The areas with economic-spatial driver such as the Zhengdong Xinqu and Economic Zone become a lead in the urban expansion. In the process, the size of plots and connectivity increase. Within the 10 km radius to the center, the urban land of the city became more compact, especially in the rapid urbanizing directions. But beyond that distance, the developmental pattern could be compact or loose. By comparing, landscape is slightly changed along the corridor with less economic drivers. These results call for particular attentions of planners to optimizing urban spatial structure.